The overall goal of this program is to increase our understanding of the cellular and molecular events controlling the formation of connective tissue during wound repair. The current experiments are designed to determine the physiological role of a newly identified peptide. Connective Tissue Growth Factor (CTGF). CTGF is a cysteine-rich mitogenic peptide that binds heparin and is secreted by fibroblasts after activation with Transforming Growth Factor Beta (TGF-beta). CTGF os a member of a highly conserved family of peptides that include immediate early gene products cef10, cyr 61, fisp 12; a putative avian proto-oncogene, nov; and a drosophila gene, twisted gastrulation, tsg, that controls medial mesoderm induction during dorsal-ventral axis pattern formation, a process also controlled by TGF-beta related peptides (dpp, scw). In the adult mammal, CTGF functions as a downstream mediator of TGF-beta1 action on connective tissue cells, where it stimulates cell proliferation and extracellular matrix synthesis. CTGF does not appear to act on epithelial cells or immune cells. Because the biological actions of TGF-beta are complex and effect many different cell types, CTGF may serve as a more specific target for selective intervention in processes involving connective tissue formation during wound repair or fibrotic disorders. Molecular and cell biological techniques will be used to produce recombinant CTGF and fragments of CTGF for investigation of its action on cells in culture and in animal models of wound repair. Specific antibodies will be produced to neutralize the biological actions of CTGF, and these will be used to determine the relationship of CTGF-function to TGF-beta's action on target cells. Agents that inhibit the induction of CTGF expression by TGF-beta will be used for the same purpose. In situ hybridization will be used to determine the normal cell and tissue pattern of CTGF gene expression during tissue regeneration (wound repair) and embryogenesis. Transgenic mice will be generated to determine if the TGF-beta response element in the CTGF promoter is responsible for regulation of the cell and tissue specific expression of the CTGF gene. In other transgenic mice, the CTGF gene will be over-expressed in tissues prone to fibrosis, to determine if CTGF alone is sufficient to induce a fibrotic lesion. These experiments could lead to the development of new animal models for fibrotic disease and to new therapeutic approaches for the control of fibrotic disorders in humans.